How do I choose a good knife?

There are so many choices now; I have a thin narrow Cutco for some things, a bread knife, a couple of Santokus and chef's knives. I've acquired them over many years. I like them all. You might start with 2 or 3.

Global has several lines for women, even for lefthanded, but my favourites are the knives aimed for the food processing industry, often with plastic grips -simple and inexpensive.

Treat it like a pair of sneakers; you need to try it "on" before you buy it. What works for one person may be extremely uncomfortable for another.
And for the record, expensive does NOT equal "best", but cheap (most often) equals "bad quality". Find a middle ground.

I have several expensive knives including a couple of pricey chef's knives, but the one I reach for most often is my 8-inch Victorinox with the fibrin handle. It's a bit more than the $20 it used to be, but still under $40. It just feels really good in my hand. A good knife to start with and you may find you need look no further.

What is a "nice knife" for a "female buyer"? Do you mean the knife is lighter weight?

Yes, 14" chef's knives exist. And longer ones too. I've seen cooks use sword-like tools to mince shallots.

I agree with everyone that The Best knife is the one that feels best, for most of the jobs you do in the kitchen. I have favorite knives for different jobs/techniques. I often recommend Global knives for first time "nice knife" female buyers.

it might be blasphemy, but if you want an all purpose supersharp serrated knife, few are better than Cutco. They're guaranteed for life and when it dulls, you send it back and they send it back to you razor sharp.

I take the knives I use the most to be sharpened at least once a year. Try to find someone who uses stones as opposed to a wheel. Unless you get your knife sharpened on a wheel every week, that knife will last well past your grandchildren's lives. Unless it's made of ceramic and you drop it on the ground (they shatter.)

While I agree with the gist of what Cynthia wrote about length, I've never seen a 14" chef's knife so I'm guessing that's a typo. 10's are common in restaurant kitchens but personally I prefer an 8-inch blade. Nothing to do with height though, at least not in my case, I just find I'm more accurate with one.

One other thought: There used to be a rule about forged blades being superior to stamped designs. That no longer holds true so be wary of anyone who tells you differently. Knife steels and production technology has changed a lot over the years.

In addition to the great advice above, don't spend a lot of money unless you have some knife skills. If you think it might benefit you, perhaps some of the best money a person could spend is to take a class in knife skills. Any good class will give you a chance to use different weight and sized knives, as Cynthia mentions above. I remember that a few years ago, Cooks Illustrated recommended a $20 Victorinox chef's knife over many pricier models. You need a chance to try them out, so look for a store (or class) that will give you that opportunity.
p.s. And learn how to sharpen them - it makes all the difference

Longevity shouldn't be a concern with any quality knife provided you take care of it (don't run it through the dishwasher, rinse immediately after use, especially after cutting citrus, steel it regularly...) Never buy a knife set. Make darn sure what you buy is comfortable and feels balanced in your hand under realistic conditions. Never listen to anyone's recommendations for a particular knife. Their hand is different than yours and their grip may be different as well. Price does not equate to quality and neither does weight. Make certain you try both heavy styles (Henckels and Wüsthof for example) and lighter designs (in particular Victorinox). You may well find a lighter style suits you better and is less fatiguing.

Knife discussions in culinary school were all very well and good, but it was finally years in restaurant kitchens that taught me that one extremely important factor in choosing a knife is one's height. I am short. A massive 14" long chefs knife was impossible for me to use. I felt like I was trying to slice carrots with a sword. A 10" chefs knife is perfect for me. I gave the 14-incher to my 6' tall prep cook. He loved it.

Go to a restaurant supply store and find a sales associate. Tell him what you want and how much you want to spend. Things like: size, style, whether you want stainless or carbon steel, any special requests (like a handle that fits a very large or very small hand.) They will have everything from "bargain basement but not total crap" to "super fancy forged by hand by a master craftsmen before being quenched in the blood of virgins" price range and features list. If that sales associate doesn't know what he's talking about, find someone who does.

Hold the knife in your hand and make sure it feels good in the hand and is nicely balanced. Have a look at the knife itself - you want a knife whose blade tang goes all the way through the handle of the knife. The place where the blade joins the handle should be easy to clean and solid (well-joined.) No gaps or crannies to catch gunge breed bacteria. You want the cutting edge to run the entire length of the blade, and not taper off toward the handle. And don't be afraid to shop around. If you fall in love with a particular knife at the restaurant supply, look around on the internet to see if you can order it from a wholesaler or something similar for cheaper.